An International Reigstry of Werner Syndrome, supported for the past 8 years by an expiring NIH MERIT Award to Dr. Martin, will be expanded in order to: 1) ascertain and genotype additional pedigrees from around the world; 2) establish and cryopreserve lymphoblastoid cell lines,primary skin fibroblasts and SV40 transformed fibroblast cultures representative of a range of WRN mutations; 3) initiate a collection of sib-pairs (wild type versus heterozygotic carrier) for retrospective and long-term prospective studies of the susceptibility of heterozygotes to various types of neopolasms. All cell culture materials as well as red blood cells (for glycophorin mutation studies) will be made available to investigators associated with this Program-Project grant. Cultures rpresentative of a variety of mutations will also be made available to the general community of invetigators via deposits with the Institute Data Base will be established as a password-protected Local Area Network for Program-Project investigators and as a limited access vehicle for scientists and physicians.